It need not be an enemy. It can be anyone. And projection is often what we are feeling or thinking.
We all do it to some extent, some of us more than others. And it's the basic psychological mechanism behind paranoia.
But .. you are correct, it does go along with paranoia - and therefore - the person they attack is to them “the enemy”.
I’ve more often than not seen it as a direct attack verbally upon another person .. while if they had been just thinking about it or feeling bad .. they would not have necessarily voiced that opinion.
I don’t agree that we “all” do it to some extent. The reason I believe that is because not “all” people have a psychological disorder of that magnitude.
As for the liberals .. they appear to be wired that way.